Configure / Finetune the Microsoft Exchange search / indexing feature

Abstract: Sometimes there is a urgent need to fine tune a server feature. For example if you are dealing with a low CPU/RAM issue on MS Exchange and need to solve that as soon as possible. So to solve these kind of resource issues you wish to Configure the Microsoft Exchange search / indexing feature so that it didn´t need so much CPU/RAM.

At first you might try to disable the content indexing as written here, however this caused the following issue:

exch01: Database copy 'EXCHMB1-EG-3GB' on server 'exch01' has content index catalog files in the following state: 'Disabled'. If you need to activate this database copy, you can use the Move-ActiveMailboxDatabase cmdlet with the -SkipClientExperienceChecks parameter to forcibly activate the database.

So your next attempt is to "fine tune" that, but there is only less information available what can be done. So I decided to write this small howto, which explains some possible options.

1.) Disable some File formats indexed by Exchange Search

Per default the Microsoft Exchange Search (FAST search) index a wide range of file formats (as seen here) which can be checked via:

Get-SearchDocumentFormat

If you for example wish to disable the indexing from JPG and GIF files (as every email might contain such elements in a signature) you can run the following (you need to run the Exchange Powershell via "run as admin"):

Some companies might also wish to disable the indexing from ZIP files, to avoid performance issues in there environment due to large ZIP attachments or to close a possible vulnerability (with malware in compressed ZIP files) via

This is a per server configuration. You need to login into the server and need to perform the change directly on the server where you wish to disable the file format.

After the change restart the Exchange Search Host Controller service and Microsoft Exchange Search service on the server where you implemented the changes or better reboot the whole server.

2.) Change the maximum size file that can be indexed by Exchange Server

By default, the maximum size file that can be indexed by Exchange Server 2013 on-premises is 32 MB. To increase this size limit, you must add the following registry key on all CAS and multi-role servers in your organization (as written here). To change the maximal attachment size which will be indexed to 40 MB change the key to 40. Example